Hierarchical Process Composition: Dynamic Maintenance of Structure in a Distributed Environment.

摘要

This dissertation is an in depth study of a method, called Hierarchial Process Composition (HPC), for organizing, developing, and maintaining large distributed programs. HPC extends the process abstraction to nested collections of processes, allowing a multiprocess program in place of any single process, and provides a rich set of structuring mechanisms for building distributed applications. The emphasis in HPC is on structural and architectural issues in distributed software systems, especially interactions involving dynamic reconfiguration, protection, and distribution. The major contributions of this work come from the detailed consideration, based on case studies, formal analysis, and a prototype implementation, of how abstraction and composition interact in unexpected ways with each other and with a distributed environment. HPC ties processes together with heterogeneous interprocess communication mechanisms, such as TCP/IP and remote procedure call. Explicit structure determines the logical connectivity between processes, masking differences in communication mechanisms. HPC supports one-to-one, parallel channel, and many-to-many (multicasting) connectivity. Efficient computation of end-to-end connectivity from the communication structure is a challenging problem, and a third-party connection facility is needed to implement dynamic reconfiguration when the logical connectivity changes. (kr)